W: GPG error: http://download.opensuse.org Release: The following signatures were invalid: KEYEXPIRED 1386276565
W: Failed to fetch http://th.archive.ubuntu.com/ubuntu/dists/natty-backports/main/source/Sources 404 Not Found
W: Failed to fetch http://th.archive.ubuntu.com/ubuntu/dists/natty-backports/restricted/source/Sources 404 Not Found
W: Failed to fetch http://th.archive.ubuntu.com/ubuntu/dists/natty-backports/universe/source/Sources 404 Not Found
W: Failed to fetch http://th.archive.ubuntu.com/ubuntu/dists/natty-backports/multiverse/source/Sources 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.